The present invention relates generally to a power converter system and, more particularly, to a bridgeless Power Factor Correction (PFC) circuit for a power converter circuit.
FIG. 1 shows a conventional totem-pole bridgeless PFC circuit 100. The PFC circuit 100 includes first to fourth diodes 102, 104, 106, and 108, and a capacitor 110. The first and third diodes 102 and 106 are connected in series and are a first connection across the capacitor 110, and the second and fourth diodes 104 and 108 are connected in series and are a second connection across the capacitor 110. A first node 112 located between the first and third diodes 102 and 106 is connected to a current supply 116, while a second node 114 located between the second and fourth diodes 104 and 108 is connected to an inductor 118, which is connected in series with the current supply 116. The PFC circuit 100 further includes a first switch 120 and a second switch 122, which are respectively coupled across the second and the fourth diodes 104 and 108.
During a positive half cycle of the current supply 116, the second switch 122 is closed and the first switch 120 is open, such that the current supply 116 charges the inductor 118 by way of the second switch 122, the third diode 106, and the first node 112. When the charging is finished, the second switch 122 is opened and the first switch 120 is closed, such that the inductor 118 discharges to release the stored power by way of the first diode 102, the first switch 120, and the second node 114. On the other hand, during the negative half cycle of the current supply 116, the first switch 120 is closed and the second switch 122 is open, such that the current supply 116 charges the inductor 118 by way of the first diode 102, the first switch 120, and the second node 114. When the charging is finished, the first switch 120 is opened and the second switch 122 is closed, such that the inductor 118 discharges to release the stored power by way of the second switch 122, the third diode 106, and the first node 112.
It would be advantageous to have either a circuit with more efficient energy conversion or a less costly circuit.